Extension Methods in .NET 2

The tags say .NET 2.0; If you are using C# 3.0 (i.e. VS 2008) and targetting .NET 2.0, you can do this by declaring the ExtensionAttribute - or (easier) just reference LINQBridge.

namespace System.Runtime.CompilerServices
{
[AttributeUsage(AttributeTargets.Assembly | AttributeTargets.Class |
AttributeTargets.Method)]
public sealed class ExtensionAttribute : Attribute { }
}

With this in place, extension methods will work in .NET 2.0 with C# 3.0.